öOO 
David H. Dolley 
tions are filier as compared with the cells without intracellulär axone. 
This is in agreement with tlie comparison between large and small cells 
niade by Retzius (1890). In addition, tlie staining reaction, though it is 
the point most affected by the functional condition, differs. 
But, after being thus separated broadly, distinct differences are to 
be found within the groups. The fundamental characteristic of nerve 
cell activity which had been determined in the work upon the Purkinje 
cell was the existence of a definite and constant resting type, the cell 
from which activity Starts and to which it recedes on recovery from 
activity. Applying this experience, the fhst attempt was to determine 
the resting types for the two groups. The smaUest cells in each group, 
showing none of the characteristics of activity, fitted properly the re- 
quirements for a resting type, but there was for each group the coni- 
plicating finding that there was a much larger type of cell possessing 
the same attributes (Figs. 1 and 8, 13 and 18 respectively). The only 
conclusion was that there existed two sub-groups within each main 
group. For example, comparing the ceUs in Tables VI and VII, both 
of cells without intracellular axones, one series Starts with a cell volume 
of 15,732, the other with an average volume of 42,768, a difference distinct 
to the eye alone if cut in the same plane. Pointing to the same con- 
clusion just as strongly was the apparent fact that given two ceUs of the 
same size in either main group, they might differ from each other ex- 
tremely in the points which previous experience had taught distinguished 
activity from fatigue (compare Fig. 11 with Fig. 3, Fig. 13 with Fig. 19, 
Fig. 16 with Fig. 21). The cells upon which measurements had been 
niade were then so separated and this dmsion into two groups possessing 
each two sub-groups was confirmed by the regulär course of their sizes 
and corresponding nucleus-plasma relation. All series of measurements 
made since then have only served to establish it further for aU ganglia. 
Since this histological analysis is only incidental and accessory to 
the main purpose of this paper, no comparison with previous analyses 
of cell types will be given with the exception of one. It is sufficient to 
say that the functional state of the ceU, the aU-important thing, has 
been neglected. However, one Investigation appears to throw much 
light and the present findings are in agreement with it. Retzius (1890), 
in his wellknown work on the nervous System of Astacus fluviatiUs, makes 
his essential division into large and small cells. The axones from the 
large cells run proximally or distally in the longitudinal commissure. 
On the contrary, the axones from the small ceUs were foUowed into the 
peripherally going nerves of the same or adjacent ganglia. The axones 
